1. Field
The present disclosure relates to a method and apparatus for transmitting and receiving a reference signal for supporting an effective beam search in a extremely high frequency (mmWave) analog beamforming communication system.
2. Description of the Related Art
In order to meet wireless data traffic demands, which have increased since the commercialization of the 4th Generation (4G) communication system, efforts to develop an improved 5G communication system or a pre-5G communication system have been made. For this reason, the 5G communication system or the pre-5G communication system is called a beyond-4G-network-communication system or a post-LTE system.
In order to achieve a high data transmission rate, implementation of the 5G communication system in an ultrahigh frequency (mmWave) band (e.g., 60 GHz band) is being considered. In the 5G communication system, technologies such as beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna technologies are being discussed as means to mitigate propagation path loss in the ultrahigh frequency band and increase a propagation transmission distance.
Further, the 5G communication system has developed technologies such as an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), an ultra-dense network, device-to-device communication (D2D), a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMP), and received interference cancellation to improve the system network.
In addition, the 5G system has developed advanced coding modulation (ACM) schemes such as hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access technologies such as filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA).
An mmWave frequency band may use a broadband frequency of several GHz in order to support rapid increase of mobile traffic. A standard specification for supporting an mmWave band is an IEEE 802.11ad (e.g., wireless gigabit alliance (WiGiG)) standard of a 60 Ghz frequency band, and companies such as Samsung Inc., Nokia Inc., Ericsson Inc., Docomo Inc., Intel Inc., Qualcomm Inc., and/or the like have developed various frequency candidate groups such as 15 Ghz, 28 GHz, 38 GHz, 44 GHz, 70 GHz, and/or the like for a next generation mobile 5G communication standard.
The mmWave frequency band has great path attenuation compared to an existing frequency band. However, the mmWave frequency may obtain a link budget required for a high antenna gain and a wireless communication by mounting a plurality of array antennas within a given physical space and applying a beamforming (BF) technology according to a short-wave characteristic of an electric wave.
In a beamforming communication system, a stable communication is possible only if best beams are applied between a base station (BS)(or it will be referred to as Node B) and a terminal (e.g., a mobile station (MS)). Further, in a case that a best beam is changed in a situation that a terminal moves, there is a need for tracing rapidly the change of the best beam. So, it is very important to provide a technology which may rapidly and correctly search a best beam between a base station and a terminal in a beamforming communication.
Recently, a scheme of providing a mobile service using an mmWave frequency band has been discussed. In this case, a handover technology of a multi-cell environment is necessary for providing a continuous and seamless service, it is very important to provide a scheme of obtaining independent channel information per base station for a terminal to select a serving base station.
So, there is a need for a technology for effectively obtaining channel information for cells and beams in a base station and terminal system which operate a plurality of analog beams.